253 Soil Matric Potential Block for Multiplexer Use
Reliable Water Measurements
No maintenance required
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported


The 253, manufactured by Watermark, is a solid-state, electrical-resistance sensing device with a granular matrix that estimates soil water potential from 0 to -200 kPa (typically, wetter or irrigated soils). It connects to a datalogger via an AM16/32-series multiplexer.

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Benefits and Features

  • Survives freeze-thaw cycles
  • Compatible with AM16/32-series multiplexers, allowing measurement of multiple sensors
  • Multiplexer connection prevents electrolysis from prematurely destroying the probe
  • Rugged, long-lasting sensor
  • Buffers salts in soil
  • Compatible with most Campbell Scientific data loggers


Technical Description

The 253 determines soil water potential by measuring electrical resistance. When the 253 is wet, electrical resistance is low. As the 253 dries, resistance increases.

The 253 consists of two concentric electrodes embedded in a reference matrix material. The matrix material is surrounded by a synthetic membrane for protection against deterioration. An internal gypsum tablet buffers against the salinity levels found in irrigated soils.

The 253's construction can allow the sensor (in some circumstances) to be left in the soil all year, eliminating the need to remove the sensor during fallow periods.

The 253 connects to a datalogger via an AM16/32-series multiplexer. Because the multiplexer contacts close only during measurement, electrical currents leading to premature degradation of the 253 are eliminated.


Measurement Range 0 to -200 kPa
Diameter 1.91 cm (0.75 in.)
Length 8.26 cm (3.25 in.)
Weight 360 g (0.8 lb)


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.


Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR216X (retired)
CR5000 (retired)
CR9000X (retired)

Measurement and Control

Product Compatible Note